1. Field
Example embodiments of inventive concepts relate to image sensor chips, and more particularly, to image sensor chips implemented as wafer stacks.
2. Description of Conventional Art
Complementary metal oxide semiconductor (CMOS) image sensors are sensing devices using CMOS. CMOS image sensors have lower manufacturing cost and smaller size than charge coupled device (CCD) image sensors having a high-voltage analog circuit and thus have an advantage of low power consumption. In addition, the performance of CMOS image sensors has been improved as compared to an early development stage, and therefore, CMOS image sensors are usually used for various electronic appliances including portable devices such as smart phones and digital cameras.
With the various uses of CMOS image sensors, the minimization of a pixel array and a driving circuit in CMOS image sensors has been demanded. In addition, high-definition images are demanded with the minimization. Therefore, approaches for meeting these demands have been researched and developed.